Methods and apparatus for transporting powder material



United States Patent [72] Inventor Neil Rudolph Wallis Cariad, Goring-On-Thames, Oxfordshire, England [2]] App]. No. 651,025'

[22] Filed July 3, 1967 [45] Patented Nov. 24, 1970 [32] Priority July 8, 1966 [33] Great Britain [54] METHODS AND APPARATUS FOR TRANSPORTING POWDER MATERIAL 17 Claims, 4 Drawing Figs.

[51] Int. Cl B65g 53/40 [50] Field olSearch 302/56,51, 52, 57, 17

[56] References Cited UNITED STATES PATENTS 1 ,749,8 17

3/1930 Hermsdorf 1,970,405 8/1934 Thomas 2,868,590 1/1959 Allen et al. 3,355,222 ll/l967 Neely Primary Examiner-Andres H. Nielsen Attorney-Shoemaker & Mattare ABSTRACT: A method and apparatus for transporting powder material wherein a container for the powder material has a conduit extending downwardly thereinto and a jet extending upwardly thereinto to adjacent the lower end of the conduit, and means connected to vibrate at least a portion of the conduit in the vicinity ofthe lower end to enhance the flow of gas-entrained powder.

l 4 I 'llli I Patented Nov. 24, 1970 Sheet 1 or 2 m N 6 v N I NEIL. FLLDOLPH LJHLLIS Patented Nov. 24, 1970 3,542,43fi

Shaw 2 of 2 rwvapvratL N611. PHDOLPH LJHLL/s 4 r'razruc S This invention relates to methods and apparatus for transporting powder material and is particularly concerned with.

transportation methods based on the production of a suspension of powder material in a gas/The word gas" is used herein to include a gas or a mixture of gases such, for example,

as air.

One particular use of methods and apparatus in accordance with the invention is in the application of powder coating material to articles and it is-an object'of the invention to {arm vide particularly efficient methods and apparatus for supply ing powder coating material entrained in air to manual electrostatic powder coating equipment.

From one aspect, the invention consists in a method of transporting powder material, wherein a suspension of the powder in a gas is formed in a conduit by supplying gas under pressure through a jet which opens into one end of the conduit, and wherein at least a portion of said conduit in the vicinity of said one end is substantially vertical and is vibrated.

From another aspect, the invention consists in ap'paratus for transporting powder material including a container for the material, a conduit extending downwardly into the container, a jet extending upwardly to the end of the conduit in the container, means for supplying gas under pressure to said jet and means for vibrating said end of said conduit.

From yet another-aspect, the invention consists in a method of applying powder coating material to an-article, wherein a suspension ofpowder in a gas is formed in a-conduit by supplying gas under pressurethrough ajet which opens into one end of said conduit, wherein at least a portion of said conduit in the vicinity of said one end is substantially vertical and is vibrated, wherein the suspended powder is transported along the conduit to a distributing head and, wherein an electrostatic field is maintained betweenthe head, or a part of the head, and the article to be coated, so that powder leaving the distributing head is charged and is thus attracted towards the article.

Preferably the lower end of the conduit is arranged to vibrate along its longitudinal axis and may be arranged to terminate in a substantially vertical member mounted on a vibrating platform arranged at the base of a container for the powder material. Vibration oi the platform may be produced lectromagnetically or pneumatically and preferably the frequency of the vibration is in the sonic range.

The upper end of the jet may be substantially coplanar with the lower end of the tubular member, or the jet may extend a short distance into the mouth of the tubular member, Normally, the jet and the tubular member willbe coaxial and the cross-sectional area of the lower end of the tubular member may be, for example, at least thirty times the cross-sectional area of the jet. Preferably the internal surface of the tubular member is designed as a venturi tube. The gas may be supplied to the jet, for example, at a pressure of 50 lb. per square inch and the relationship between the cross-sectional areas of the conduit and the jet may be such that the pressure in the conduit is, for example, 1 lb. per square inch.

It is to be understood that compressed air or other gas issuing from the jet and entering the tubular member creates a region of subatmospheric pressure in the mouth of the tubular member and in the region surrounding said mouth. Vibration of the platform on which the tubular member is mounted causes at least a partial fluidisation of the powder in this region, so that the low pressure causes powder to be drawn into the tubular member and entrained in the air issuing from the jet. The air and the powder entrained therein travel along the conduit to a distributing head or other utilisation device.

One method of performing the invention will now be described with reference to the accompanying diagrammatic drawings in which:

FIG. 1 is a sectional side elevation of the lower end of a powder container including a vibrator for use in a. method in accordance with thepresent invention;

FIG. 2 is a plan view of the vibrator illustrated in lilG. ll removed from the powder container;

FIG. 3 is a plan view of the lower part of the vibrator separated from the remainder of the apparatus along the line Y-Y of FIG. 1; and

HO, 4 is a detail drawing showing the arrangement of the feed pipes in the vibrator.

The powder container illustrated in FIG. ll includes a hopper 1 and a vibrator 2 secured to the base of the hopper by means of bolts 3 and nuts 4-, a seal between thehopper and the vibrator being provided by means of an annular ring 5. The casing of the vibrator includes an upper ring 6, a lowerring 7 and a base 8, secured together by means of five screws '9 (FIG. 2). The upper and lower rings consist of rigid synthetic resin materia', whereas the base is in the form ofa metal cup. A thin diaphra {m 10 of-resilien't material is clamped between the upper ri 1g 6 and the lower ring 7.

Mounted on the diaphragm 10 is a metal tubular member ll provided at its upper end with a threaded cap 12 and a deformable metal insert 13 for attaching the lower end of an exit conduit M. The tubular member it is supported by means of a spider 15 consisting of three legs welded to the tubular member, each leg being provided with a mounting ring it at its free end. Three pillars it? are secured to the diaphragm it) by means offlat nuts l8. Each of the pillars l7 passes through the ring 16 at the free end of a respective one of the legs of the spider l5 and the spider is spaced from the diaphragm 10 by'rneans of three distance pieces l9. The rings at the ends of two of the legs ofthe spider are free to move on their respective pillars, but the third ring is secured to its pillar by means ofa nut 20.

Mounted in the centre of the diaphragm 10 is a jet tube 21, the lower end of which is threaded to receive a flat nut 22 above the diaphragm and a rigid member 23 below the diaphragm. The lower face of the rigid member 23 is cut away to form a cavity 2d and'two. radial holes are drilled in this member as indicated in FIG. 4, one to provide a passage 25 extending to the base of the jet tube 21 and the other to provide the passage 26 terminating in an opening 27 in the cavity 2d. Connecters 28 and 2% are screwed into the member 23 to communicate with the passages 25 and 26 respectively.

The lower boundary-of the cavity 24 is formed by the upper surface of a second rigid'member 30 which is urged against the peripheral lower wall of the member 23 by means of a spring 3i located at its upper end by means of a boss 32 on the member 30 and at its lower end in a recess 33 formed in the base 8. The member 30 is movable relatively to the member 23 and these two members are located: with respect to one another by means of a spigot 3d fixed in the member 30 and slidable in a drilling in the central boss 35 of the member 23.

As can be seen from FIG. 3, the base 8 is provided with two connecters 36 and 37 coupled respectively to the connecters 28 and 29 by rubber pipes 38 and 39 (FIG. 4). Thus the connecter 36 provides an air inlet to the jet tube 21 and the connecter 37 provides an air inlet to the cavity 24.

When the apparatus is in use, the hopper l is filled with powder and the remote end of the conduit id is connected to a utilisation device. In particular, the utilisation device may he a manual electrostatic powder gun of the kind described and illustrated in my U.S. Pat. application No. 638,328. Air supplies are connected to the two connectors 36 and 37 with the result that the diaphragm 10 is vibrated and the air issued from the jet tube 21 entrains the powder which is kept in motion by the vibration of the diaphragm l0 and conducts it through the tubular member ill and the conduit 14 to the utilization device. it will be seen that the internal surface of the tubular member 11 is formed as a venturi tube to assist in the entrainment of the powder by means of the air from the jet tube 21.

The air supply connected to the connecter 37 produces air pressure in the cavity 24 which, after a predetermined period of time, becomes sufficient to force apart the two members 23 and 30 against the restraining action offithe diaphragm l0 and the spring 3E. The air then escapes around the periphery of the cavity and leaves the vibrator casing through holes 40 drilled in the recess 33. As a result of the reduction of the air pressure in the cavity 24, the members 23 and 30 are brought together again by means of the spring 31 and the diaphragm 10. This operation is repeated cyclicly and causes the required vibration of the diaphragm 10. This vibration is imparted to the tubular member 11, the jet tube 21 and to the supply of powder in the hopper 1, with the result that the powder is maintained in a more or less fluidised state. The air issuing from the jet creates a region of subatmospheric pressure below the lower end of the tubular member 11 and the vibration of the powder ensures that there is a continuous supply of easily-movable powder available in this region from which it can be drawn into the member 11. The conduit 14 is arranged to be a loose fit in the top of the hopper i so that the vibrations also extend along a substantial part of the conduit to prevent the possibility of blockages forming in the conduit.

it is to be understood that if it is desired to vibrate the diaphragm l electromagnetically rather than pneumatically. the members 23 and may bereplaced by a core of magnetic material surrounded by a solenoid energised by alternating current of a suitable frequency.

1 claim:

1. A method of transporting powder material, comprising the steps of:

a. flowing said powder to an inlet end of a powder disposed in surrounding relation to of said conduit;

b. supplying gas under pressure through a jet into said eonduit inlet end;

c. entraining the powder material in the gas under pressure and causing it to flow in said conduit; and

d. vibrating at least a portion of said conduit in the vicinity of said inlet end to enhance the flow of the gas-entrained powder.

2. A methodas claimed in claim 1, wherein the said portion of said conduit vibrates along its longitudinal axis;

3. A method as claimed in claim 1, wherein the said conduit at said one end terminates in a substantially vertical tubular member mounted on a vibrating platform arranged at the base of a container for the powder material.

4. A-method as claimed in claim 3, wherein vibration of the platform is produced pneumatically.

5. A method as claimed in claim, 3, wherein vibration of the platform is produced electromagnetically.

6. A method as claimed in claim 3, wherein the platform is vibrated at sonic frequencies.

conduit, said said inlet end 7. A method as claimed in claim 3. wherein the upper end of the jet is substantially coplanar with the lower end of the tubular member.

8. A method as claimed in claim 3, wherein the jet extends a short distance into the mouth ofthe tubular member.

9. A method as claimed in claim 3, wherein the jet and the tubular member are coaxial.

10. A method as claimed in claim 1, wherein the cross-sectional area of the conduit is at least thirty times the cross-sectional area of the jet.

11. Apparatus for transporting powder material, compris ing:

a. a container for the powder material;

b. a conduit extending downwardly into the container and having an open lower end defining an inlet to said conduit; ajet extending upwardly within the container to the inlet in substantially coaxial relationship end of said conduit therewith; means for supplying gas under pressure to said jet for entraining said powder and causing said gas-entrained powder to flow into and along said conduit; and e. vibrating means connected with said conduit for vibrating said conduit inlet to enhance the flow of gas-entrained powdertherethrough.

12. Apparatus as claimed in claim 11, wherein said conduit terminates at said end in a substantially vertical tubular member mounted on a vibrating platform.

13. Apparatus as claimed in claim 12, wherein the jet is also mounted on said platform.

14. Apparatus as claimed in claim 13, wherein said platform is generally circular, wherein the axis of said jet and the axis of said tubular member pass through the centre of said platform.

15. Apparatus as claimed in claim 14, wherein the periphery of said platform is stationary and vibration is imparted to a central portion of said platform.

16. Apparatus as claimed in claim 15, wherein the tubular member is mounted on said platform by means of a spider which retains the lower end of the tubular member spaced above the platform.

17. Apparatus as claimed in claim 12, including a first rigid member secured beneath said platform, a second rigid member movable relative to said first rigid member and defining an annular cavity therewith, means for introducing air under pressure into said cavity and spring means urging said second rigid member towards said first rigid member to close said cavity. 

